DENVER -- A gunman who opened fire inside a Safeway Distribution Center Sunday afternoon, killing one person and injuring five, was shot to death after a confrontation with police, 7NEWS reported.

"The officers confronted the suspect who was armed with the handgun. He fired at us, we fired at him," said Denver police Chief Gerry Whitman.

After the standoff and confrontation with the gunman ended, officers searched the 1.3 million-square-foot building and found the body of one employee who was apparently shot to death.

Four other employees were taken to the hospital. Two are in critical condition, one person is in serious condition and one person is in fair condition. A Denver police officer who was shot in the leg during the confrontation was also taken to the hospital in serious condition. His injuries were not considered to be life-threatening.

The shooting occurred at about 3 p.m. inside the Safeway Denver Distribution Center on the 4600 block of East Stapleton Drive, near the intersection of Interstate 70 and Colorado Boulevard.

Witnesses said a disgruntled employee walked in to the produce area, fired at least five shots and tried to set several fires.

"I seen him. He was like about 20 feet away from me. He was just shooting and lighting fires. He wanted to turn the building on fire," said Safeway worker Jesus Lopez. "I just ran. Everybody just ran out."

"We just got off our forklifts and ran to the exit door," said another Safeway worker.

The gunman started multiple fires in one location and one fire in another location. The sprinkler system inside the building kicked off immediately and contained most of the fires. Firefighters couldn't enter the building because the gunman was still at large inside, 7NEWS reported.

Workers ran out of the building as about 50 police officers arrived with their weapons drawn and surrounded the area. Police set up a barrier around the perimeter of the store and worked to get the gunman and the other employees out of the building.

The warehouse is massive -- stretching several city blocks -- so it took officers some time to find the gunman, and then later, to clear the scene to make sure that there were no other suspects or victims were inside.

During that time, employees huddled on a pile of gravel near the corner of the lot, waiting for the standoff between the gunman and the police to be over and to learn when they could reenter.

The shooting prompted police to shut down Interstate 70 in the area until 5 p.m.

The identities of the suspect and the victim have not been released.

The motive for the shooting is unclear.

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